You can download the map toolkit from the Zomboid forums, which contains everything you need to recreate your neighbourhood, your office, your hometown, a dystopian future city, or wherever else you fancy murdering zombies.

Project Zomboid is still in alpha, with current tasks including from all-2D artwork to 3D models and environments. You can buy into the alpha for $14.99 (and get the finished game, of course). A demo's on offer too, so you can try it first.